Pregnancy test line getting lighter.

LaNette β€’ πŸ’”πŸ’”πŸ’”πŸ’”πŸ€°πŸŒˆπŸŒˆ

2 days ago I took a frer test and it was positive. It was a faint line but it was pretty clear. Today I took another test, again a frer and there is a very very faint line. To the normal eye it looks like a negative test but when you look closely there is a very faint line. Much lighter than from 2 days ago. I’m so confused. Could this be a chemical? 2 days ago I did not use my fmu and today I did. Help!?